The invention relates to an apparatus for pressure regulation in a hydraulic system, in particular in vehicle anti-skid braking systems (ABS).
Such equipment is found in vehicle brake systems that have ABS. The vehicle brake systems are mounted at the wheels of the vehicle and provided with brake pressure lines that lead to the hydraulic brake system. To generate braking pressure and hence the braking action, a master brake cylinder is actuated using a foot pedal. Modern vehicles have ABS systems built in as well, which also generate a brake pressure for automatically adapted braking in anti-skid operation. To this end, sensors are mounted adjacent the wheels to indicate the danger of skidding, and via a control unit they control a motor, return pump and magnetic regulating valve, for example, to produce suitable pressure changes in the brake lines compared with the pressure of the master brake cylinder. Equalizing the pressure in the master brake cylinder produces pulsations that can be felt by the driver at the foot pedal.
German Offenlegungsschrift 31 07 963 discloses a brake fluid pressure control apparatus for ABS systems. This apparatus provides a pressure fluid supply line between the master cylinder and the control valve. To eliminate a brake pedal feedback caused by pressure changes, check valves are disposed in the brake system and a bypass line having a thottling action is provided. Despite the provision of such throttle restrictions in the brake system, however, perceptible pulsations do reach the vehicle brake pedal. The metal, rigid-pressure damper chamber known from German Offenlegungsschrift 26 43 860 is likewise incapable of adequately eliminating the pulsations that arise.